1. Field of the Invention
The present invention relates to a slide fastener in which an upper stopper material having a U-shaped section and made of thermal plastic synthetic resin is attached to a stopper portion of a fastener tape such that the upper stopper material is located adjacent an end portion of the fastener elements mounted along a side edge of the fastener tape by fusing with ultrasonic heating, high-frequency heating or heating with a heater under a pressure.
2. Description of the Related Art
Conventionally, an upper stopper device is attached by welding thermal plastic synthetic resin and generally, a film-like or monofilament-like material is attached to a fastener tape or the top surface of the fastener tape. As for a upper stopper device of a slide fastener disclosed in, for example, Japanese Patent Application Publication No. 48-37421 (patent document 1), mono-filament of thermal plastic synthetic resin, for example, polyester resin or polyamide resin is, cut out into a predetermined length and bent into a U shape and then press-fitted to an inverted portion or a leg portion of coil-like fastener elements to be molded by welding and fixed thereto at the same time. In an upper stopper device of a slide fastener disclosed in, for example, Japanese Patent Application Publication No. 49-36975 (patent document 2), on a bead formed on a side edge of a fastener tape is mounted a coil-like fastener element of the same size as the bead and then, a short filament material is placed on this fastener element, bead and the top face of part of the fastener tape and these are fused together and hardened so as to form and settle a stopper portion.
However, because in these well-known slide fasteners, their upper stopper portions are molded on only the top face of the fastener tape by welding, the mounting strength thereof to the fastener tape is weak. Thus, the stopper portion on which the largest impact force is applied when a slider flange strikes is likely to be separated from the fastener tape easily, so that this kind of the stopper portion cannot bear a long-term usage. The top face of each of the slide fastener and its components mentioned in this specification refers to an outside surface in an attachment component of the slide fastener while its bottom face refers to an inside surface.
Conventionally, to solve such a problem, for example, Japanese Utility Model Application Laid-Open No. 62-148116 (patent document 3) and Japanese Utility Model Application Publication No. 5-31932 (patent document 4) have proposed slide fasteners in which each upper stopper is never separated, the upper stopper device being composed of synthetic resin having a large welding strength. According to these publications, the upper stopper device sandwiches upper and lower faces of a side edge portion of a fastener tape and respective ends of the upper stopper on the side of a tape main body on top and bottom surfaces thereof are joined together in a bridge-like configuration through a gap or an opening made among composition yarns of woven or knitted fabric of the fastener tape, so that they are integrally welded. According to the patent document 3, at this time, an entire inner peripheral face of the stopper device is welded with a side edge portion of the tape at the same time, while according to the patent document 4, the inner peripheral face of the upper stopper is not welded with a tape except an end portion of the upper stopper near the inside of the tape.
As a result, the document 3 proposes a stopper portion which secures a strong fixing condition having a large weld portion area capable of enduring a violent strike by a slider sufficiently and has an extremely high reliability capable of bearing a hard contact by a strong sliding force of the slider. According to the document 4, only the end portion of the upper stopper on the side of the tape main body is welded strongly and the inner peripheral face on the side of the tape main body except the end portion of the upper stopper is not welded. Thus, when the slider strikes, the upper stopper swings around the end portion, so that a kind of buffering effect is generated, thereby protecting the upper stopper from damage.
Because the upper stopper of each of the slide fasteners disclosed in the patent documents 3 and 4 is composed of a flat smooth surface, a large contact area with an inside face of the slider is generated. Consequently, when a sliding operation for opening the slide fastener is started, its sliding resistance is large and thus, there exists a feeling of heaviness. Further, the flat configuration of the upper stopper not only increases the sliding resistance of the slider but also largely affects a separation resistance due to catching with the slider at the time of start of the sliding.
Generally, the closing of the slide fastener by the sliding operation of the slider is achieved by a contact between opposing end faces of the right and left upper stoppers and joint column portions of the slider, and a contact between the end portions on the tape main body of the upper stopper and front faces of slider flange portions when the slider is slid. Because a quite large striking force due to the sliding operation of the slider acts upon the upper stopper when the upper stopper contacts the slider, part of the slider may sometimes catch the upper stopper. For the reason, the above-described faults occur.
Generally, when the slide fastener is mounted on object clothes, a bottom face of the fastener is directed directly to the human body, so that it makes a direct contact with the skin depending on the case. Thus, because the upper stopper is small, if it projects from the bottom face of the fastener tape, it gives itchy feeling to the skin. When the slider is started, the upper stopper portions of the slide fastener are nipped with the fingers while a pull tag is nipped with the finger of the other hand. At this time, some people may sense a feeling of discomfort because hardness feeling of the upper stopper is transmitted to the fingers.
The itchy feeling and feeling of hardness are sensed particularly because a portion making contact with the skin on the edge on the side of the tape main body of the upper stopper projects outward from the surface of the fastener tape main body. In the patent documents 1 to 4, it is understood that the edge on the side of the tape main body of any upper stopper projects outward from the surface of the fastener tape main body.
Further, because the conventional stopper portion is integrated by fusing with the fastener tape through its entire contact faces, the amount of heat necessary for fusing entirely needs to be increased. As a result, not only the stopper portion but also the fastener tape are supplied with heat more than necessary, so that embrittlement due to over-heating occurs. Consequently, the stopper portion likely cracks and drops out and further, the mounting portion of the stopper is likely to be strict-structured.
The present invention has been achieved to solve such conventional problems and a specific object of the present invention is to provide a upper stopper of a slide fastener, particularly a U-shaped upper stopper made of synthetic resin mono-filament material, which is formed and fixed by welding on a side edge of the fastener tape by heating with a pressure, the upper stopper being not made embrittle or hardened by the welding, so that sliding resistance at the time of sliding of the slider by the upper stopper is reduced and itchy feeling and feeling of discomfort based on the configuration of the upper stopper are eliminated.